Jet-pump oil-return system



Sept. 22, 1970 K. G. NEELEY 3,529,421

JET-PUMP OIL-RETURN SYSTEM 7 Filed Nov. 18, 1968 Z/RESERVOIR V 9 5 II!!! 7 I 41H 7 I 6- I l0 3 III/I "'ENTOR. KE/ TH ELEY United StatesPatent 3,529,421 JET-PUMP OIL-RETURN SYSTEM Keith G. Neeley, HighlandPark, Calif., assignor to K. M. White Company, Louisville, Ky., acorporation of Kentucky Filed Nov. 18, 1968, Ser. No. 776,429 Int. Cl.F15b 15/18, 21/04; F04f /02 US. Cl. 60-52 7 Claims ABSTRACT OF THEDISCLOSURE The invention is of an automatic oil scavenging unit forhydraulic elevator systems powered by a jet pump. Oil leaking fromaround the elevator actuating jack is collected and fed to thelow-pressure input side of a jet pump. The jet pump is driven byhigh-pressure liquid taken from the output side of the main elevatoractuating pump. The output of the jet pump is delivered to the hydraulicstorage tank for the system.

BACKGROUND The invention is in the field of hydraulic elevator actuatingsystems and pertains specifically to a means for collecting oil whichleaks from the main actuating piston in such systems, and returning itto the hydraulic storage tank.

An important problem associated with systems of this type has been thenecessity for a separate source of power to drive whatever means wasutilized to collect and transfer oil leaking from the associatedhydraulic system. In addition, there have been associated problems ofcapacity, location, Wear and tear, and expense inherent in such systems.

The system and pump device of the invention provide a fully automaticoil-return system requiring a minimum of space, and providing a greatflexibility as to its location with respect to the hydraulic elevatorsystem.

It is an objective of this invention to provide an oilreturn system ofthe character indicated which operates automatically at all times whenthe main hydraulic pump is in operation.

It is a further objective of this invention to provide an automaticoil-return system With substantially no moving parts.

It is a further objective of this invention to provide an automaticoil-return system which is hydraulically operated.

It is still another objective of this invention to provide an automaticoil-return system which requires no independent mechanical power sourcefor its operation, and which does not noticeably affect the capacity ofthe main elevator-pump system to operate the elevator.

SUMMARY Basically, the system of the invention is comprised of a jetpump with a high-pressure inlet side attached to the output of the mainhydraulic pump which drives the elevator jack, a low-pressure input sideconnected to a collecting collar mounted upon the main hydraulic jackand around the actuating piston, and an output which connects to thehydraulic storage tank for the elevator system.

The jet pump of the invention is comprised of an inlet jet tube and anexhaust tube mounted along a common axis within the cross bar of ahollow T-shaped tubular housing. The hollow stem of the T-shaped housingcomprises the low-pressure inlet for the pump. A ball-type check valvedisposed within said low-pressure inlet prevents oil from flowing backthrough the discharge line to the collecting collar.

3,529,421 Patented Sept. 22, 1970 The invention has the advantage ofproviding a high capacity automatic oil return system at a minimum ofcost.

The system has the additional advantage of requiring a minimum of space,as the pump is very small and requires only three small lines toincorporate it within the elevator system.

In addition the system has been found capable of lifting return oil tothe extent of at least 26 feet at sea level, thus providing considerablelatitude in its positioning with respect to the remainder of thehydraulic system.

Other objectives, advantages, and various further features of noveltyand invention will be pointed out or will occur to those skilled in theart from a reading of the following specification in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic layout of asimplified hydraulic elevator system incorporating the invention; and

FIG. 2 is a cross-sectional view of the jet pump of the invention andforming part of the layout of FIG. 1.

DETAILED DESCRIPTION Referring now to FIG. 1, a simplified hydraulicelevator system is depicted. A main hydraulic pump 1 delivers liquidfrom a reservoir 2 through a control valve 3 to a main actuating jack 4.When pump 1 is in operation, hydraulic fluid under high pressure isdelivered to jack 4, causing actuating piston 5 to move out of cylinder6 and raising the elevator car (not shown). As some hydraulic fluid willinevitably leak from the actuating cylinder around piston 5, acollecting collar or manifold 7 is mounted to cylinder 6 at the point ofexit of actuating piston 5.

Oil collected by collar 7 is drawn off by jet pump 8 and delivered toreservoir 2. As the oil leaves collar 7 it is passed to a scavenge pump8 by way of a filter 9, as shown incorparated in a branch-Y body, forclean-out and maintenance convenience.

In accordance With the invention the scavenge pump 8 is self-operatingfrom high-pressure hydraulic fluid bled from the output side 10 of thehydraulic pump 1, so that whenever pump 1 is in operation, pump 8 willbe Operative to scavenge oil which has collected in collar 7. Valve 3 isa control valve which delivers hydraulic fluid under high pressure tojack 4 to move the elevator up, and permits fluid to escape fromcylinder 6 to move the elevator down, and the flow which is bled fromthe pump-output line 10 is so insubstantial as to result in nonoticeable impairment of elevator-jack operation, even for existingelevator installations.

Referring now to FIG. 2, the scavenge pump is seen to comprise a simplejet pump including a tubular substantially T-shaped body 12 having across bar member 13 with a stem 14 extending therefrom.

The high-pressure inlet end 15 of pump 8 has a pipe fitting or nipple 16inserted therein, to facilitate attachment of the high-pressurehydraulic feed line and to sup port an internal part 17 of the jet pump.Part 17 is an orifice member or bushing having a restricted bore 18 andis adjustably threaded to the inner end of bore 19 of the fitting 16.The outer end 20 of bore 18 has a counterbore of polygonal cross sectiondesigned to permit axial adjustment of member 17 within fitting 16, asby means of an Allen-type wrench.

A short length of tubing 21, which may be brass tubing, is carried bymember 17 and forms the high-pressure inlet for the jet pump. The outerend 21a of tube 21 may be soldered within the bore 18, care being takenthat the longitudinal axis thereof is aligned with a. bore 22 in crossbar 13 of the pump body.

The output end 24 of the jet pump carries an end-connection fitting ornipple 25 similar to fitting 16, and a length of tubing 26, larger indiameter than tube 21, is secured, as by solder, in the counterbored endof a bushing 28 having threaded engagement in the bore of fitting 25;the counterbore 27 is adjacent an Allen-type socket formed in theremainder of the bushing bore, for axialadjustment purposes. Care mustbe taken in mounting tubes 21 and 26 to assure that their longitudinalaxes are aligned, such that tube 21 points directly down the center oftube 26.

The low-pressure inlet 30 of. pump 8 is at the Open end of stem leg 14of the T-shaped body 12. Threaded into inlet 30 is a ball-check valve 31which permits oil to flow only in the direction of pump 8.

In operation, high-pressure liquid from pump enters the high-pressureinlet of pump 8, where it is forced through tube 21, creating a smallhigh-speed jet of hydraulic fluid which is directed down the center oftube 26. This high-pressure jet causes substantially all of themolecules of matter Within tube 26 to move through outlet 24, whichinduces a partial-vacuum condition within chamber 32, being theremaining or otherwise unoccupied internal volume of the jet-pump body12. With the vacuum thus created, atmospheric pressure will cause oilcollected within collar 7 to flow through filler 9 and into chamber 32.Oil in chamber 32 is then picked up by the jet emerging from tube 21 andforced in the direction of reservoir 2.

The spacing between the inner ends 21b of tube 21 and 26a of tube 26 iscritical, but may be readily set by Allen-type adjustment. For bestresults the hydraulic jet emerging from tube 21 should be aimedprecisely down the center of tube 26. If the spacing between tubes 21and 26a of tube 26 is critical, but may be readily set by pump isgreatly reduced. A spacing of -in. to A -in. is recommended for a pumphaving tubing of the following dimensions: inlet high pressure tube 21,-in. (O.D.) standard brass tubing, and outlet tube 26, t in. (O.D.)standard copper tubing. A pump constructed in this manner, and run withhydraulic pressure of 150 p.s.i. at inlet 19, and with a flow of 1.7gallons per minute through pump 8, established 80% to 95% of a perfectvacuum in chamber 32, with the average being about 89%. Under theseconditions the bled-off flow was less than 1 percent of the flowdelivered to operate the jack 4, and there was no noticeable impairmentof operation, for the otherwise standard system involved.

The automatic oil-return system of the invention and its associated jetpump thus simply and efliciently provide for continuous scavenging ofoil which leaks from the elevator actuating cylinder; this result isachieved by using only a small fraction or bleed from the same hydraulicpressure which creates the leakage. The scavenger system isautomatically operative whenever the elevator is going up, and at othertimes when the main hydraulic pump is in operation.

While the principles of the invention have been described in connectionwith the above specific apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationto the scope of the invention as set forth in the accompanying claims.

What is claimed is:

1. In a hydraulic elevator system including a main hydraulic pump, anactuating jack and a fluid storage tank, an improved automatic returnsystem for returning hydraulic fluid which leaks from the actuating jackto the fluid storage tank comprising:

means attached to the main jack to collect the fluid which leakstherefrom, said collector means having an outlet for the fluidcollected:

a constricted bleed connection from the main hydraulic pump outputincluding a jet pump having first and second inlets and one outlet;

means connecting the first of said inlets to the output side of the mainhydraulic pump;

means connecting the second of said inlets to the outlet of saidcollector means; and

means connecting the outlet of said jet pump to the liquid storage tank,so that whenever the main hydraulic pump is operating, the automatic oilreturn system will also be in operation.

2. The system of claim 1, in which said bleed constriction limitsjet-pump flow to a relatively small fraction of the flow required foroperation of said jack.

3. The system of claim 1, further including a check velve mounted withinsaid second inlet of said jet pump so as to prevent oil from flowingfrom said pump toward said collector means.

4. The system of claim 3, wherein said jet pump is comprised of aT-shaped pipe fitting:

an input jet comprising a length of tubing of selected dimensions, andmeans for mounting said tubing within and substantially coaxiallyaligned with the cross bar of said T-shaped fitting;

an exhaust tube comprised of a length of tubing substantially larger indiameter than said input jet, and means for mounting said outlet tubewithin said fitting so that the longitudinal axis thereof is coextensivewith the longitudinal axis of said input jet tube, and with the adjacentends of said input jet and exhaust tubes spaced a preselected distanceapart.

5. The system of claim 4 wherein the means for mounting said input jettubing within said T-shaped fitting includes a first tubing flangeadapted to thread into one end of the cross bar of said T-shapedhousing, and a tubular bushing adapted to thread into the inside end ofsaid first flange, said input jet tubing being telescopically fittedinto said bushing and attached thereto.

6. The system of claim 5 wherein the means for mounting said exhausttube within said pump housing includes a second tubing flange adapted tothread into the other end of the cross bar of said T-shaped housing, anda tubular bushing adapted to thread into the inside end of said secondflange, said exhaust tube being telescop ically fitted into saidsecond-mentioned bushing and attached thereto.

7. In a hydraulic system wherein a mechanism is driven by a hydraulicactuating device, which device is operated by hydraulic fluid suppliedunder pressure by a main hydraulic pump; an improved system forreturning hydraulic actuating fluids which have leaked from saidactuating device to the hydraulic system from which they escaped,comprising; means to collect the hydraulic actu ating fluid which hasleaked from the hydraulic actuating device, said collecting means havingan outlet for the liquid collected, a jet-type vacuum pump, having ahigh pressure input, an intake and an outlet, and means to connect thehigh pressure input of said jet pump to the output side of said mainhydraulic pump, means to connect the intake of said jet pump to theoutlet of said collector means; and means to connect the output side ofsaid jet pump to a hydraulic reservoir which supplied the hydraulicsystem served by said main pump, so that the hydraulic pressure which isrelated to such liquid leakage also actuates the jet pump which pumpscollected leakage back to the reservoir.

References Cited UNITED STATES PATENTS Re. 11,755 7/1899 Muir 103-2621,474,454 11/1923 Telfer. 1,737,870 12/ 1929 Telfer. 2,136,239 11/1938Ernst 92-172 XR 2,43 8,245 3/1948 Gregg 60-52 2,575,241 ll/l95l White.

EDGAR W. GEOGHEGAN, Primary Examiner US. Cl. X.R. 92-80; 103-262 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 9 421 DatedSeptember 22, 1970 Inventor(s) G. NEELEY It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 3, line 34, cancel "26a of tube 26 is critical,

but may be readily set by" and substitute therefor "26 is too great ortoo small the efficiency of the jet--- SIGNED hNb SEALED FE a 2 1971 15mAwait:

M mum: E. SGHUYLER, .m. Awning Officer Goflhissioner of Patents

